The present invention relates to laser cutting installations in which the parts and skeleton of the processed sheet material workpieces are unloaded automatically.
Laser cutting machines are now widely employed for processing of sheet metal workpieces since the laser will cut the sheet metal rapidly and the laser beam and/or the workpiece can be moved by a guidance system to enable precise cutting of parts. One type of common laser cutting machine for processing large sheet metal workpieces has a work support over which there is a movable bridge, and the laser cutting head is supported on the bridge. The bridge can be moved along the workpiece support to effect cutting of the workpiece in the longitudinal direction, and the laser cutting head can be moved along the bridge to effect cutting in the transverse direction. Illustrative of such machines is Erlenmaier U.S. Pat. No. 6,586,706 and Kilian U.S. Pat. No. 5,304,773.
Loading machines for the sheet metal workpieces have been widely employed for punch presses and laser cutting machines and generally involve suction devices which are arranged in a grid that can be adapted to the size of the sheet metal workpieces to be picked up and carried by the loading device. Generally, such loading devices will pick up the sheet metal and then rotate or otherwise move to deposit the sheet on the workpiece support in the desired position. Illustrative of such loading devices is that illustrated and described in Leibinger et al U.S. Pat. No. 6,066,531.
The cutting operation will frequently produce numerous small parts and a skeleton which must be removed from the workpiece support. Although the operator may remove and sort them manually, this extends the processing time and reduces the productivity of the laser cutting machine. Accordingly, various types of units have also been provided for removing from the workpiece support the cut parts and skeleton. It has also been proposed to leave small webs of material retaining the cut parts in the skeleton so that the cut workpiece can be lifted as a unit by a suction arrangement; the remaining webs are then broken to release the parts from the skeleton after it has been transported to a separation station.
Typically, the workpiece support has a grid formed by two superposed layers of metal slats arranged on their sides on end with the slats in each layer being parallel and the slats of one layer being perpendicular to those of the other layer. Use of a pick up device with a grid of suction devices to pick up the parts and skeleton requires relatively complex programming to actuate the suction devices over each part and an unbroken surface area of the skeleton.
It is an object of the present invention to provide a novel laser cutting installation including a movable unloading unit for picking up the cut parts and skeleton from the workpiece support and transporting them to a discharge station.
It is also an object to provide such a laser cutting installation which can be fabricated relatively readily and which is simple to operate.